I'm not really sure how companies in Europe are compared to American companies. What I know, applies to American companies, but will hopefully help you as well.
For one; don't undersell your self. If you can make some money and make a career of it, do it.
Two, try looking around at various small (even non-comics) companies that could use art as paid contract work. Doing some work for these companies can beef up a good resume and shows the comic companies that you have a level of professional experience under you.
Go to conventions or other likes and let the companies know you exist and are very interested in the field. Also, take the time to meet writers and artists in the field., Build up your contacts with everyone in the field. If you have questions, many artists are willing to speak with you if you message them via a polite e-mail. They know the field the best.
Keep up your portfolio. Most companies don't want to see old work. Keep the work fresh (now, if there is one or two peices that are just fantastic and older, that's okay as long as a large majority of the portfolio is fresh and new. These pieces can also act as boosts of memory for people who had seen your work before. They'll be like, "Oh yeah, I remember this piece." ) Along the lines of portfolio building, keep your work varying. Have character designs, illustrations, and various short stories or scenes. Show how you handle a talking scene and how you handle an action scene. Show your pencils, inks and colors. (Or if you just want to focus on one of these; have that in your portfolio. Many profession level artists who have DA accounts often post up high-res files of their work for other people to practice on. Just remember to credit the artist, and if you post it online credit their work and let them know. They love seeing how other people handle inks over their pencils, or colors of their inks.)
Start a web comic. Webcomics are becoming more and more popular (there are many sites: comicfury, smackjeeves, tapastic, and mangamagazine to name a few). Many companies want to see their prospective artists having a webcomic because it can tell them a lot about the person. It can show how you handle story, plot development, character development, pacing, scene changes, in general time management handling, and other general stuff that they would need to know. remember, companies are making an investment in you, so they want to be sure that they can make it back.
I wouldn't say you would need a degree, but those who get a specialty degree I feel have a slight leg up on most people because their schools do help them build their contections and point out and help get rid of bad habits and weak points quicker as opposed to some one self teaching themself. But, you can always get other people to give you critiques and help you through the rough patches.
I hope this helps you at least some.
